diagnostic imaging of stroke

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  • C.N.S.

    Stroke

  • Mohamed ZaitounAssistant Lecturer-Diagnostic Radiology Department , Zagazig University HospitalsEgyptFINR (Fellowship of Interventional Neuroradiology)-Switzerlandzaitoun82@gmail.com

  • Knowing as much as possible about your enemy precedes successful battle and learning about the disease process precedes successful management

  • Vascular Territoriesa) Vascular Anatomyb) Cerebral Arterial Territoryc) Watershed Infarctsd) Lacunar Infarctse) Posterior Reversible Encephalopathy Syndrome (PRES)f) Cerebral Venous Territoryg) Cerebral Venous Thrombosis

  • a) Vascular Anatomy :1-Internal Carotid Artery2-Circle of Willis3-Middle Cerebral Artery4-Anterior Cerebral Artery5-Persistent Carotid-Basilar Connections

  • 1-Internal Carotid Artery :-Cervical (C1) : doesnt branch within the neck-Petrous (C2) : fixed to bone as the ICA enters the skull base , so a cervical carotid dissection is unlikely to extend intracranially-Lacerum (C3) : no branches-Cavernous (C4) :*Meningohypophyseal trunk arises from the cavernous carotid to supply the pituitary , tentorium and dura of the clivus*Inferolateral trunk also arises from C4 to supply the 3rd , 4th & 6th cranial nerves as well as the trigeminal ganglion

  • -Clinoid Segment (C5) : the carotid rings are two dural rings that mark the proximal & distal portions of the clinoid segment of the ICA , the carotid rings prevent an inferiorly located aneurysm from causing intracranial SAH with rupture-Supraclinoid (C6-C7) : gives off several key arteries :1-Ophthalmic artery :-Supplies the optic nerve , it takes off just distal to the distal carotid ring in 90 % of cases and can be used as a landmark for the distal ring-Aneurysms located superior to this ring can result in subarachnoid hemorrhage2-PCOM :-Is an anastomosis to the posterior circulation -A fetal PCA is a variant supplied entirely by the ipsilateral ICA via an enlarged PCOM3-Anterior choroidal artery :-Supplies several critical structures , despite its small size , it supplies the optic chiasm , hippocampus and posterior limb of the internal capsule

  • Ophthalmic artery

  • Lateral projection of a left common carotid artery injection that displays the order of branching in the intracranial carotid including 1: ophthalmic , 2: posterior communicating , 3: anterior choroidal and 4: anterior cerebral arteries

  • 2-Circle of Willis :

  • *Critical small arteries arising from the Circle of Willis:-The A1 segment of the ACA travels above the optic nerves and give off the recurrent artery of Heubner which supplies the caudate head & anterior limb of the internal capsule , the A1 segment also gives rise to the medial lenticulostriate perforator vessels which supply the medial basal ganglia-Just outside the circle of Willis , the MCA gives rise to the lateral lenticulostriate perforator vessels to supply the lateral basal ganglia including the lateral putamen , external capsule and the posterior limb of internal capsule

  • Recurrent artery of Heubner infarction

  • Medial lenticulostriate arteries infarction

  • Lateral lenticulostriate infarction , note the inverted comma-shaped hypodense left lenticular nucleus (red dotted lines) , the anterior limb of the left internal capsule (yellow arrow) is also involved by the ischemic infarction while the head of the left caudate nucleus (blue dotted lines) is spared

  • -The PCOM travels between the optic tract and the 3rd cranial nerve giving off anterior thalamoperforator vessels , PCOM aneurysm may cause cranial nerve III palsy-The PCA gives off thalamoperforators to supply the thalamus -Artery of Percheron is a variant where there is a dominant thalamic perforator supplying the ventromedial thalami bilaterally and the rostral midbrain arising from a P1 PCA segment , an artery of Percheron infarct will result in bilateral ventromedial thalamic infarction with (pattern 1) or without (pattern 2) midbrain infarction (the infarct may be V-shaped if the midbrain is involved , deep venous thrombosis may also result in bilateral thalamic infarcts

  • DSA of the left vertebral injection , lateral (A) and anteroposterior (B) views and a coronal CTA image (C) show a large unpaired thalamic perforating artery (arrows) arising from the proximal P1 segment supplying the bilateral thalami (i.e. Artery of Percheron)

  • FLAIR at the level the thalamus (A&C) and midbrain (B&D) show bilateral paramedian thalamic and midbrain involvement (pattern 1), notice the hyperintense signal intensity along the pial surface of the midbrain interpeduncular fossa representing the V sign (BandD)

  • Axial FLAIR (AandB) and DWI (CandD) images at the level of the thalamus (A&C) and midbrain (B&D) demonstrate infarction of the bilateral paramedian thalami without midbrain involvement (pattern 2)

  • Axial FLAIR through the midbrain show a V-shaped hyperintense signal intensity along the pial surface of the midbrain at the interpeduncular fossa (the V sign)

  • -The anterior choroidal artery is the most distal branch of the ICA , it supplies the optic chiasm , hippocampus and posterior limb of the internal capsule

  • Anterior choroidal artery infarction , acute infarct is noted involving the posterior limb of right internal capsule as well as the head of the right hippocampus

  • 3-Middle Cerebral Artery :

  • -2D frontal view following right ICA injection , the appearance of the carotid circulation is normal , Note the early bifurcation of MCA (normal variant)1 ICA cervical segment2 ICA vertical petrous segment3 ICA horizontal petrous segment4 presellar (Fischer C5) ICA6 horizontal (Fischer C4) intracavernous ICA9 ophthalmic artery10 & 11 proximal and distal supraclinoid segment ICA12 posterior communicating artery13 anterior choroidal artery14 internal carotid artery bifurcation15 A1 segment of ACA17 recurrent artery of Heubner20 proximal A2 segment ACA21 callosomarginal branch ACA28 pericallosal branch of ACA31 M1 segment of MCA32 lateral lenticulostriate arteries33 bifurcation/trifurcation of MCA34 anterior temporal lobe branches of MCA35 orbitofrontal branch of MCA43 sylvian point44 opercular branches of MCA45 sylvian (insular) branches of MCA

  • 4-Anterior Cerebral Artery :

  • 5-Persistent Carotid-Basilar Connections :-Overview of persistent fetal anterior-posterior connections :*A number of carotid to basilar connections are formed during embryogenesis , these fetal anterior-posterior circulation connections normally regress before birth*Occasionally , a fetal carotid-basilar connection may persist after birth , each anomalous connection is named for the structures adjacent to its course in the head & neck

  • -Persistent Trigeminal Artery :*The most common persistent carotid-basilar connection and has an association with aneurysms*The persistent trigeminal artery courses adjacent to the trigeminal nerve , angiography shows a characteristic trident or tau sign (resembling the Greek letter ) on the lateral view due to the arterys branching system*Saltzman type I connects to the basilar artery while Saltzman type II connects to the superior cerebellar artery

  • Lateral left common carotid angiogram obtained during the arterial phase shows the persistent trigeminal artery coursing posteriorly to supply the distal basilar artery , the tau configuration (dotted lines) is also apparent

  • MRA shows lateral persistent trigeminal artery Saltzman type 1 (arrows) , note the hypoplastic vertebral artery (arrowhead)

  • -Less common carotid to basilar connections :*The hypoglossal , otic and proatlantal intersegmental arteries are rare persistent carotid-basilar connections-Persistent primitive hypoglossal artery (HA) :*Artery named for its association with 12thnerve*Second most common after PTA , persistent vessel arises from ICA at C1 to C3 segments , enters the skull through anterior condylar or hypoglossal canal (not through the foramen magnum) and courses posteromedially to continue as terminal segment of the VA and BA*The contralateral VA, if present, generally terminates in the posterior inferior cerebellar artery

  • b) Cerebral Arterial Territory :1-Posterior Inferior Cerebellar Artery2-Superior Cerebellar Artery3-Branches from vertebral and basilar artery4-Anterior Choroidal artery5-Lenticulostriate arteries 6-Anterior cerebral artery 7-Middle cerebral artery8-Posterior cerebral artery

  • 1-Posterior Inferior Cerebellar Artery (PICA in blue)-The PICA territory is on the inferior occipital surface of the cerebellum and is in equilibrium with the territory of the AICA in purple which is on the lateral side -The larger the PICA territory , the smaller the AICA and vice versa

  • Left-sided PICA infarction , notice the posterior extension , the infarction was the result of a dissection (blue arrow)

  • Left sided PICA infarction, in unilateral infarcts there is always a sharp delineation in the midline because the superior vermian branches do not cross the midline but have a sagittal course, this sharp delineation may not be evident until the late phase of infarction, in the early phase, edema may cross the midline and create diagnostic difficulties, infarctions at pontine level are usually paramedian and sharply defined because the branches of the basilar artery have a sagittal course and do not cross the midline, bilateral infarcts are rarely observed because these patients do not survive long enough to be studied but sometimes small bilateral infarcts can be seen

  • 2-Superior Cerebellar Artery (SCA in grey)-The SCA territory is in the superior and tentorial surface of